I've been meaning to try out salad in a jar for my lunches at work. The most appealing aspect of it was the fact that by layering the ingredients, you can keep it from getting soggy or losing it's individual component flavours over time. With the timing of my lunch (if any, most days), I wanted to be able to at least have a healthy option instead of turning to the A&W next to my workplace so often. Additionally, they can keep for up to a week, so you can save a few bucks when buying your vegetables.
thekitchn.com has a great link to some ideas on how to do these most effectively.